To accurately control the speed of a motor vehicle, such as a car, a truck, a bus, a tractor or the like, suitable accelerations and decelerations have to be determined and applied. For environmental and cost reasons, these accelerations and decelerations should be performed in a fuel efficient manner.
A suitable speed of the motor vehicle in a certain situation or position can depend on a number of parameters, such as specific traffic situations or road conditions. Such road conditions include among other parameters a desired speed for a part of the road where the vehicle is, e.g. depending on speed limits, a condition of the road surface, which, as is well known, can get slippery due to rain or ice, or an uphill or downhill slope being present.
Today, there are many electronic aids available for determining such parameters being used for determining the suitable speed of the motor vehicle. Such electronic aids now being publicly available include electronic positioning systems, such as the Global Positioning System (GPS) and other corresponding positioning systems and electronic maps. Such positioning systems can provide three dimensional positioning information, i.e. information relating to latitude, longitude and altitude. Also, the electronic maps can include speed limits being set for different sections of the road as well as topology information. Also, weather conditions, such as temperature, rain and/or snowfall are provided to the vehicle by sensors on the vehicle itself or by information being transmitted to the vehicle from one or more outer sources.
The prior art system shown in patent application US2005/0085974 uses such electronic aids to some extent in order to minimize fuel consumption. In this prior art system, GPS information is used for determining instantaneous information, of that moment and electronic map information is used for determining future positions. Further, a road incline in a specific position is determined by the use of electronic sensors on the vehicle, and by extrapolations from such road incline determinations and a topology surrounding the vehicle can be estimated. These parameters are then used for determining a throttle opening such that, for example, gravity is taken into account when adjusting the throttle opening.
However, control of the amount of fuel being injected in an engine or adjustment of the throttle opening (i.e. performing adjustment of the speed of the vehicle) by only taking into account such parameters that minimize the fuel consumption, as in the prior art, may lead to a driving behavior that is irritating to other road users. Thus, drivers of vehicles following such a motor vehicle might find that the driving behaviour of the motor vehicle is annoying, since it does not follow well established driving norms.
Further, a speed control system not following such well established driving norms might also be perceived as non-intuitive and unacceptable by the driver of the motor vehicle itself, which might cause him to disconnect or override the speed control system. Such disconnection or overriding of the speed control system would jeopardize fuel efficiency, since the driver then disobeys the suggestions of the speed control system, which would lead to a higher fuel consumption.
Thus, there is a need in the prior art for a solution which offers a fuel efficient acceleration behaviour for a motor vehicle and at the same time is regarded by the driver of the motor vehicle himself as well as the drivers of surrounding vehicles as having an understandable and acceptable driving behaviour.